Proton rich nuclei at and beyond the proton drip line in the Relativistic Mean Field theory

Ground state properties of proton-rich odd-$Z$ nuclei in the region $55\le Z \le 73$ are studied in the relativistic mean field (RMF) theory. The RMF equations are solved by using the expansion method in the Harmonic-Oscillator basis. In the particle-particle channel, we use the state-dependent BCS method with a zero-range $\delta$-force, which has been proved to be effective even for neutron-rich nuclei. All the ground state properties, including the one-proton separation energies, the ground state deformations, the last occupied proton orbits and the locations of proton drip line, are calculated. Good agreement with both the available experimental data and the predictions of the RHB method are obtained.Comment: the version to appear in Progress of Theoretical Physics, more discussions adde

Information Theoretic Limits of State-dependent Networks

We investigate the information theoretic limits of two types of state-dependent models in this dissertation. These models capture a wide range of wireless communication scenarios where there are interference cognition among transmitters. Hence, information theoretic studies of these models provide useful guidelines for designing new interference cancellation schemes in practical wireless networks. In particular, we first study the two-user state-dependent Gaussian multiple access channel (MAC) with a helper. The channel is corrupted by an additive Gaussian state sequence known to neither the transmitters nor the receiver, but to a helper noncausally, which assists state cancellation at the receiver. Inner and outer bounds on the capacity region are first derived, which improve the state-of-the-art bounds given in the literature. Further comparison of these bounds yields either segments on the capacity region boundary or the full capacity region by considering various regimes of channel parameters. We then study the two-user Gaussian state-dependent Z-interference channel (Z-IC), in which two receivers are corrupted respectively by two correlated states that are noncausally known to transmitters, but unknown to receivers. Three interference regimes are studied, and the capacity region or the sum capacity boundary is characterized either fully or partially under various channel parameters. The impact of the correlation between the states on the cancellation of state and interference as well as the achievability of the capacity is demonstrated via numerical analysis. Finally, we extend our results on the state-dependent Z-IC to the state-dependent regular IC. As both receivers in the regular IC are interfered, more sophisticated achievable schemes are designed. For the very strong regime, the capacity region is achieved by a scheme where the two transmitters implement a cooperative dirty paper coding. For the strong but not very strong regime, the sum-rate capacity is characterized by rate splitting, layered dirty paper coding and successive cancellation. For the weak regime, the sum-rate capacity is achieved via dirty paper coding individually at two receivers as well as treating interference as noise. Numerical investigation indicates that for the regular IC, the correlation between states impacts the achievability of the channel capacity in a different way from that of the Z-IC

Effective shell model Hamiltonians from density functional theory: quadrupolar and pairing correlations

We describe a procedure for mapping a self-consistent mean-field theory (also known as density functional theory) into a shell model Hamiltonian that includes quadrupole-quadrupole and monopole pairing interactions in a truncated space. We test our method in the deformed N=Z sd-shell nuclei Ne-20, Mg-24 and Ar-36, starting from the Hartree-Fock plus BCS approximation of the USD shell model interaction. A similar procedure is then followed using the SLy4 Skyrme energy density functional in the particle-hole channel plus a zero-range density-dependent force in the pairing channel. Using the ground-state solution of this density functional theory at the Hartree-Fock plus BCS level, an effective shell model Hamiltonian is constructed. We use this mapped Hamiltonian to extract quadrupolar and pairing correlation energies beyond the mean field approximation. The rescaling of the mass quadrupole operator in the truncated shell model space is found to be almost independent of the coupling strength used in the pairing channel of the underlying mean-field theory.Comment: 15 pages, 5 figure

The electrical behaviour of rat connexin46 gap junction channels expressed in transfected HeLa cells

Pairs of human HeLa cells expressing rat connexin46 were used to study the electrical properties of gap junction channels with the dual voltage-clamp method. The steady-state conductance (g j,ss) had a bell-shaped dependence on transjunctional voltage (V j). The parameters of the Boltzmann fit were: V j,0=42mV, g j,min=0.12, z=2.5 (pipette solution: K+ aspartate−; 27°C). The Boltzmann parameters were sensitive to the ionic composition of the pipette solution (KCl, K+ aspartate−, TEA+ Cl−, TEA+ aspartate−). The Vj-dependent inactivation of the junctional current I j was approximated by single exponentials (exceptions: two exponentials with KCl at V j≥75mV and K+ aspartate− at V j=125mV). The time constant of inactivation (τi) decreased with increasing V j and was sensitive to the pipette solution. The larger the ions, the slower the inactivation. Recovery from inactivation followed a single exponential. The time constant of recovery (τr) increased with increasing V j. Single-channel currents showed a main state, several substates and a residual state. The corresponding conductances γj,main and γj,residual decreased slightly with increasing V j; extrapolation to V j=0mV yielded values of 152 and 28pS, respectively (K+ aspartate−; 37°C). The values of γj,main and γj,residual were dependent on pipette solution. The ratio γj,main/γj,residual increased with increasing ionic size, suggesting that the residual state impairs ion permeation more severely than the main state. The γj,main data suggest that the ionic selectivity of Cx46 channels may be controlled primarily by ionic size. Compared with hemichannel results, docking of connexons may modify the channel structure and thereby affect the ionic selectivity of gap junction channels. The open channel probability at steady state (P o) decreased with increasing V j. The parameters of the Boltzmann fit were: V j,0=41mV, z=2.2 (K+ aspartate−; 27°C

Probing composite Higgs boson substructure at the HL-LHC

The Higgs boson may well be a composite scalar with a finite extension in space. Owing to the momentum dependence of its couplings, the imprints of such a composite pseudo Goldstone Higgs may show up in the tails of various kinematic distributions at the LHC, distinguishing it from an elementary state. From the bottom up, we construct the momentum-dependent form factors to capture the interactions of the composite Higgs with the weak gauge bosons. We demonstrate their impact in the differential distributions of various kinematic parameters for the pp -> Z*H -> l+l-bb over bar channel. We show that this channel can provide an important handle to probe the Higgs\u27 substructure at the HL-LHC

Neutrinos from Off-Shell Final States and the Indirect Detection of Dark Matter

We revisit the annihilation of dark matter to neutrinos in the Sun near the WW and tt kinematic thresholds. We investigate the potential importance of annihilation to WW* in a minimal dark matter model in which a Majorana singlet is mixed with a vector-like electroweak doublet, but many results generalize to other models of weakly-interacting dark matter. We re-evaluate the indirect detection constraints on this model and find that, once all annihilation channels are properly taken into account, the most stringent constraints on spin-dependent scattering for dark matter mass 60 GeV < mX < mt are derived from the results of the Super-Kamiokande experiment. Moreover, we establish the model-independent statement that Majorana dark matter whose thermal relic abundance and neutrino signals are both controlled by annihilation via an s-channel Z boson is excluded for 70 GeV < mX < mW. In some models, annihilation to tt* can affect indirect detection, notably by competing with annihilation to gauge boson final states and thereby weakening neutrino signals. However, in the minimal model, this final state is largely negligible, only allowing dark matter with mass a few GeV below the top quark mass to evade exclusion.Comment: 22 pages, 5 figure